1. Field of the Invention
The present invention relates to an image projection device, a light/dark-level processing method, and a computer-readable storage medium.
2. Description of the Related Art
Conventionally, there have been known techniques of equalizing the intensity of light on a projection screen in an image projection device such as a projector that projects an image of contents. For example, there has been a technique of equalizing the intensity of light on a projection screen by designing an optical system so as to collect more light at a longer distance from a projection lens (light source).
An image projection device that projects a projection image in a diagonal direction enables projection on a large screen from a short distance. This kind of device such as an image projection device with a short focus lens as a projection lens have different distances to the projection lens in some cases by several times between screen areas, one closer to the projection lens and the other farther away from the projection lens. Thus, it is difficult to equalize the intensity of light on the projection screen with the above-mentioned technique, which has caused the deterioration of visibility of the projection image.
The deterioration of visibility of a projection image can be prevented by adjusting not the intensity of light but the projection image. For example, Japanese Patent Application Laid-open No. 2006-162808 discloses a technique in which the position of a presenter is recognized from an image obtained by capturing the presentation site with a camera, and then a projection image is projected with decreased brightness in an area on the projection image corresponding to the recognized position of the presenter.
While the above-described conventional technique aims to decrease projection light shed on the presenter, it is difficult for this technique to prevent the deterioration of visibility of the projection image due to influence of the intensity of light.
Therefore, there is a need to provide an image projection device, a light/dark-level processing method, and a computer-readable storage medium that are capable of improving the visibility of a projection image.